The maximum benefit of this scientific advance is not attainable except when an oil pool is operated as a unit, and there are but few pools so operated. But the new production methods made it possible to recover an increasing proportion of the oil originally contained in the reservoir. Flowing wells were regulated to limit the amount of energy used to extract each barrel of oil, thus con serving reservoir energy to be utilized in further extraction.
Artificial water flooding of depleted oil fields, as well as artificial gas and air rejuvenation, have been successfully carried on. The use of acid in stimulating production in depleted and new fields was first begun in the United States in 1932. Hydrochloric acid was injected into the producing formation to loosen the oil, with the result that chemical methods for increasing the flow of oil have played an important part where limestone oil reservoirs occur. Between 1932 and 1939 some 14,00o wells have been treated by one process alone, and an analysis of results showed an average of more than 400% increase in the rate of production on a group of more than i,000 such wells.
Variety and efficiency of drilling tools, as well as improved drill ing methods, made it possible successfully to penetrate deeper and deeper into the earth. Devices for surveying and determin ing inclination of wells were perfected so that straighter holes could be drilled. This reduced wear on equipment and danger of the loss of wells. Intensive studies of the composition of drill ing fluids greatly aided in the control of wells and the preven tion of blowouts. These and many other improvements enabled the operator to find sands which with cruder methods frequently es caped detection, and to explore to increasing depths in search for lower sands and new pools. By 1939 the handling of oil at the surface was a totally enclosed process. The old methods of open production and storage were obsolete except as to heavy oils pro duced with little or no accompanying gas. The development of processes for the more efficient use of natural gas underground also was accompanied by the processes for more efficient use above ground, including extraction of natural gasoline and butane.
out of crude oil is a modern test-tube miracle if there ever was one. In the early days of th6 automobile, impending shortage of gasoline constantly threatened. The chemists and refining en gineers saved the day by building and operating cracking stills. Whereas in straight-refining only a gasoline yield of from 5 to 6gal. from a 42-gallon barrel of crude oil run by U.S. refineries had been obtained, the developers of cracking processes managed by 1920 to increase the yield to over io gallons. They did it by taking the heavy oils like gas oil and fuel oil which, along with gasoline, were produced in straight-refining, and re-running them in specially-built stills under tremendous heat and pressure, cracking the molecules and getting a proportion of light products —gasoline—as a result. In the space of a few years they made over the refining industry, and relieved the tension on gasoline supply.
In the intervening years there have been many improvements in cracking, and much learned respecting the resultant product. One of the most fortunate discoveries was that cracked gasoline had better anti-knock qualities than ordinary straight-run gasoline. In other words, not only did cracking save the day from a gasoline volume standpoint, adding millions of barrels annually to motor fuel supply, but it raised the quality of the product. It permitted the motor car designer to build high-compression engines, de pendent on anti-knock fuels for satisfactory operation. It gave the motorist the modern high-speed, smooth performing auto mobile engine. So extensive was the rebuilding of American refineries for cracking operations, that cracking became the backbone of the modern refinery. In 1936, for the first time, more cracked gasoline was produced by U.S. refineries than straight-run gasoline. If only straight-run gasoline had been available it is questionable whether enough crude oil could have been found, much less the necessary refinery capacity built, to fuel the world's 40,000,00o motor cars. The miracle of cracking from a conservation standpoint is that by 1938 it had saved in the ground a round billion barrels of crude oil for future use. Table XIII strikingly reveals the contribution of cracking to oil con servation.